A common question about vegan diets is whether they supply all the necessary vitamins and minerals the body requires.

Many people argue that a whole-food, plant-based diet naturally provides all daily nutrients.

Some even suggest that vegans should avoid taking any supplements.

While these recommendations come from a good place, they can sometimes do more harm than good.

Here are seven nutrients that vegans might need to supplement to ensure optimal health.

1. Vitamin B12

Certain foods often promoted as sources of vitamin B12 include unwashed organic vegetables, mushrooms grown in B12-rich soils, nori, spirulina, chlorella, and nutritional yeast.

Some believe that vegans consuming enough of these plant foods do not need to worry about vitamin B12 deficiency.

However, this belief lacks scientific evidence.

Research shows that although anyone can have low B12 levels, vegetarians and especially vegans not taking supplements are at a higher risk of deficiency (1Trusted Source, 2Trusted Source, 3Trusted Source).

Vitamin B12 is vital for many functions such as protein metabolism and forming red blood cells that carry oxygen. It also supports the nervous system’s health (4Trusted Source).

A deficiency in vitamin B12 can cause anemia, nerve damage, infertility, and increase the risk of bone and heart diseases (4Trusted Source, 5Trusted Source, 6Trusted Source).

Adults need 2.4 mcg daily, with slightly higher amounts during pregnancy (2.6 mcg) and breastfeeding (2.8 mcg).

The only scientifically validated ways for vegans to meet these requirements are by consuming B12-fortified foods or taking supplements. Common B12-fortified foods include plant-based milks, soy products, breakfast cereals, and fortified nutritional yeast.

Some plant foods seem to naturally contain a form of B12, but it’s still debated whether this form is bioavailable for humans (7Trusted Source through 13Trusted Source).

There is also no scientific support for relying on unwashed organic produce as a reliable source.

Nutritional yeast contains B12 only if fortified, but the vitamin is sensitive to light and may degrade if stored in transparent packaging (14).

Because vitamin B12 is better absorbed in small amounts, less frequent intake requires higher doses.

Vegans unable to meet their needs through fortified foods should take a daily supplement with 25–100 mcg of cyanocobalamin or a weekly dose of 2,000 mcg.

For those hesitant about supplements, checking blood B12 levels beforehand can be reassuring.

Absorption of B12 decreases with age, so the Institute of Medicine recommends adults over 51, regardless of diet, to consume fortified foods or supplements (16Trusted Source).

2. Vitamin D

Vitamin D is a fat-soluble vitamin that enhances calcium and phosphorus absorption from the digestive tract (17Trusted Source).

It also plays important roles in immune function, mood regulation, memory, and muscle recovery (18, 19Trusted Source, 20Trusted Source, 21Trusted Source).

The recommended daily intake is 600 IU (15 mcg) for children and adults, increasing to 800 IU (20 mcg) for older adults and pregnant or breastfeeding women (22).

However, some studies suggest that actual daily requirements may be higher than current RDAs (23Trusted Source).

Few foods naturally contain vitamin D, and fortified foods alone often don’t meet daily needs.

This may partly explain widespread vitamin D deficiency reports among both vegans and non-vegans worldwide (19Trusted Source, 24Trusted Source).

Vitamin D can also be synthesized through sun exposure. Typically, 15 minutes in midday sunlight without sunscreen and with most skin exposed suffices.

However, older adults, people with darker skin tones, residents of northern or colder regions, and those spending little time outdoors may not produce enough (25Trusted Source, 26Trusted Source, 27Trusted Source).

Because of the risks of UV damage, many dermatologists advise against sun exposure as a vitamin D source (28Trusted Source).

The best approach for vegans is to get blood levels tested and, if insufficient, take daily vitamin D2 or vegan D3 supplements.

While vitamin D2 is generally adequate, some evidence suggests vitamin D3 may raise blood levels more effectively (29Trusted Source, 30Trusted Source).

3. Long-Chain Omega-3 Fatty Acids

Omega-3 fatty acids fall into two categories:

• Essential omega-3s: Alpha-linolenic acid (ALA) is the only essential omega-3, meaning it must be obtained from the diet.

• Long-chain omega-3s: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are produced by the body from ALA.

EPA and DHA are critical for brain and eye structure and may support brain development and help reduce inflammation, depression, breast cancer risk, and ADHD (31Trusted Source through 36Trusted Source).

Plant sources rich in ALA include flaxseeds, chia seeds, walnuts, hemp seeds, and soybeans. EPA and DHA are primarily found in animal-based foods like fatty fish and fish oils.

Although adequate ALA intake should theoretically provide enough EPA and DHA, studies estimate only 5–10% of ALA converts to EPA and 2–5% to DHA (37Trusted Source, 38Trusted Source).

Research consistently shows vegetarians and vegans have up to 50% lower EPA and DHA blood and tissue levels than omnivores (39Trusted Source).

Experts generally recommend 200–300 mg per day of EPA and DHA.

Vegans can meet this need by taking algae oil supplements.

Reducing omega-6 fatty acid intake (from oils such as corn, safflower, sunflower, and sesame) and consuming plenty of ALA-rich foods can help improve EPA and DHA levels (40Trusted Source).

4. Iron

Iron is essential for creating new DNA, red blood cells, and transporting oxygen in the bloodstream. It also supports energy metabolism (45Trusted Source).

Insufficient iron can cause anemia, fatigue, and weakened immunity.

Men and post-menopausal women require 8 mg daily, adult women need 18 mg, and pregnant women should aim for 27 mg per day (46).

Iron comes in two forms: heme (from animal products) and non-heme (from plants) (45Trusted Source).

Since heme iron is absorbed more efficiently, vegans are often advised to consume 1.8 times the standard RDA. However, more research is necessary to confirm these higher recommendations (47Trusted Source).

Vegans with low iron intake should increase consumption of iron-rich plant foods such as cruciferous vegetables, beans, peas, dried fruits, nuts, and seeds. Iron-fortified foods like cereals, enriched breads, and some plant milks can help too (24Trusted Source, 48Trusted Source).

Cooking with cast-iron cookware, avoiding tea or coffee with meals, and combining iron-rich foods with vitamin C sources can improve absorption.

Testing hemoglobin and ferritin levels is the best way to determine if supplementation is needed.

Excess iron supplements can harm cells, block absorption of other minerals (49Trusted Source), and in extreme cases, cause convulsions, organ failure, coma, or death (50Trusted Source). Therefore, supplements should only be taken when necessary.

5. Calcium

Calcium supports bone and teeth health, muscle function, nerve signaling, and heart health.

The RDA is 1,000 mg per day for most adults, increasing to 1,200 mg after age 50 (51).

Plant-based calcium sources include bok choy, kale, mustard greens, turnip greens, watercress, broccoli, chickpeas, calcium-set tofu, and fortified plant milks or juices.

Research suggests many vegans do not meet calcium requirements (52Trusted Source, 53Trusted Source).

Some argue vegans need less calcium because they don’t consume acidic meats that increase calcium loss.

More research is needed, but evidence shows vegans consuming under 525 mg calcium daily have a higher fracture risk (53Trusted Source).

Vegans should aim for at least the RDA, ensuring they get no less than 525 mg per day, and consider supplements if dietary intake or fortified foods fall short.

6. Zinc

Zinc is vital for metabolism, immune health, and cell repair.

Low zinc intake can cause developmental delays, hair loss, diarrhea, and slow wound healing.

The RDA for adults is 8–11 mg daily, rising to 11–12 mg during pregnancy and 12–13 mg while breastfeeding (54).

Few plant foods are rich in zinc, and absorption can be hindered by phytates in plants. Therefore, vegetarians are encouraged to consume 1.5 times the RDA (54).

A recent review found vegetarians, especially vegans, tend to have lower zinc intakes and slightly lower blood zinc levels than omnivores (55Trusted Source).

To increase zinc intake, consume a variety of zinc-rich foods such as whole grains, wheat germ, tofu, sprouted breads, legumes, nuts, and seeds.

Soaking nuts, seeds, and legumes overnight, eating enough protein, and including fermented foods like tempeh and miso can enhance zinc absorption (56Trusted Source).

Vegans worried about zinc or showing deficiency symptoms may consider a daily zinc gluconate or zinc citrate supplement providing 50–100% of the RDA.

7. Iodine

Iodine is essential for healthy thyroid function, which regulates metabolism.

Iodine deficiency during pregnancy or infancy can cause irreversible intellectual disabilities (41Trusted Source).

In adults, deficiency may lead to hypothyroidism, causing fatigue, dry skin, numbness, memory issues, depression, and weight gain (41Trusted Source).

Vegans are at higher risk for iodine deficiency, with studies showing they have up to 50% lower blood iodine levels compared to vegetarians (42Trusted Source, 43Trusted Source).

The RDA is 150 mcg daily for adults, 220 mcg during pregnancy, and 290 mcg while breastfeeding (44).

Iodine levels in plant foods depend on the soil’s iodine content. Coastal areas generally produce iodine-rich plants.

Consistent iodine sources include iodized salt, seafood, seaweed, and dairy products (which absorb iodine from cleaning agents).

Half a teaspoon of iodized salt daily covers iodine needs.

Vegans who avoid iodized salt or seaweed should consider iodine supplementation.

Summary

A well-planned vegan diet can meet most nutritional needs.

However, some nutrients—especially vitamin B12, vitamin D, and long-chain omega-3s—may be hard to obtain in adequate amounts through diet alone.

Vegans who cannot meet these needs through foods and fortified products should consider supplementation.

Always consult with a healthcare professional before starting any supplement routine.